1 // native_fdm.cxx -- FGFS "Native" flight dynamics protocal class
3 // Written by Curtis Olson, started September 2001.
5 // Copyright (C) 2001 Curtis L. Olson - curt@flightgear.org
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include <netinet/in.h> // htonl() ntohl()
26 #include <simgear/debug/logstream.hxx>
27 #include <simgear/io/lowlevel.hxx> // endian tests
28 #include <simgear/io/iochannel.hxx>
30 #include <FDM/flight.hxx>
31 #include <Main/globals.hxx>
33 #include "native_fdm.hxx"
37 // The function htond is defined this way due to the way some
38 // processors and OSes treat floating point values. Some will raise
39 // an exception whenever a "bad" floating point value is loaded into a
40 // floating point register. Solaris is notorious for this, but then
41 // so is LynxOS on the PowerPC. By translating the data in place,
42 // there is no need to load a FP register with the "corruped" floating
43 // point value. By doing the BIG_ENDIAN test, I can optimize the
44 // routine for big-endian processors so it can be as efficient as
46 static void htond (double &x)
48 if ( sgIsLittleEndian() ) {
52 Double_Overlay = (int *) &x;
53 Holding_Buffer = Double_Overlay [0];
55 Double_Overlay [0] = htonl (Double_Overlay [1]);
56 Double_Overlay [1] = htonl (Holding_Buffer);
63 FGNativeFDM::FGNativeFDM() {
66 FGNativeFDM::~FGNativeFDM() {
70 // open hailing frequencies
71 bool FGNativeFDM::open() {
73 SG_LOG( SG_IO, SG_ALERT, "This shouldn't happen, but the channel "
74 << "is already in use, ignoring" );
78 SGIOChannel *io = get_io_channel();
80 if ( ! io->open( get_direction() ) ) {
81 SG_LOG( SG_IO, SG_ALERT, "Error opening channel communication layer." );
87 cur_fdm_state->_set_Sea_level_radius( SG_EQUATORIAL_RADIUS_FT );
92 static void global2net( const FGInterface *global, FGNetFDM *net ) {
93 net->version = FG_NET_FDM_VERSION;
96 net->longitude = cur_fdm_state->get_Longitude();
97 net->latitude = cur_fdm_state->get_Latitude();
98 net->altitude = cur_fdm_state->get_Altitude() * SG_FEET_TO_METER;
99 net->phi = cur_fdm_state->get_Phi();
100 net->theta = cur_fdm_state->get_Theta();
101 net->psi = cur_fdm_state->get_Psi();
104 net->vcas = cur_fdm_state->get_V_calibrated_kts();
105 net->climb_rate = cur_fdm_state->get_Climb_Rate();
108 net->cur_time = globals->get_time_params()->get_cur_time();
109 net->warp = globals->get_warp();
111 // Convert the net buffer to network format
112 net->version = htonl(net->version);
113 htond(net->longitude);
114 htond(net->latitude);
115 htond(net->altitude);
120 htond(net->climb_rate);
121 net->cur_time = htonl( net->cur_time );
122 net->warp = htonl( net->warp );
126 static void net2global( FGNetFDM *net, FGInterface *global ) {
128 // Convert to the net buffer from network format
129 net->version = htonl(net->version);
130 htond(net->longitude);
131 htond(net->latitude);
132 htond(net->altitude);
137 htond(net->climb_rate);
138 net->cur_time = htonl(net->cur_time);
139 net->warp = htonl(net->warp);
141 if ( net->version == FG_NET_FDM_VERSION ) {
142 // cout << "pos = " << net->longitude << " " << net->latitude << endl;
143 // cout << "sea level rad = " << cur_fdm_state->get_Sea_level_radius() << endl;
144 cur_fdm_state->_updateGeodeticPosition( net->latitude,
147 * SG_METER_TO_FEET );
148 cur_fdm_state->_set_Euler_Angles( net->phi,
151 cur_fdm_state->_set_V_calibrated_kts( net->vcas );
152 cur_fdm_state->_set_Climb_Rate( net->climb_rate );
154 globals->set_warp( net->warp );
156 SG_LOG( SG_IO, SG_ALERT, "Error: version mismatch in net2global()" );
157 SG_LOG( SG_IO, SG_ALERT,
158 "\tsomeone needs to upgrade net_fdm.hxx and recompile." );
163 // process work for this port
164 bool FGNativeFDM::process() {
165 SGIOChannel *io = get_io_channel();
166 int length = sizeof(buf);
168 if ( get_direction() == SG_IO_OUT ) {
169 // cout << "size of cur_fdm_state = " << length << endl;
170 global2net( cur_fdm_state, &buf );
171 if ( ! io->write( (char *)(& buf), length ) ) {
172 SG_LOG( SG_IO, SG_ALERT, "Error writing data." );
175 } else if ( get_direction() == SG_IO_IN ) {
176 if ( io->get_type() == sgFileType ) {
177 if ( io->read( (char *)(& buf), length ) == length ) {
178 SG_LOG( SG_IO, SG_DEBUG, "Success reading data." );
179 net2global( &buf, cur_fdm_state );
182 while ( io->read( (char *)(& buf), length ) == length ) {
183 SG_LOG( SG_IO, SG_DEBUG, "Success reading data." );
184 net2global( &buf, cur_fdm_state );
194 bool FGNativeFDM::close() {
195 SGIOChannel *io = get_io_channel();
197 set_enabled( false );
199 if ( ! io->close() ) {